In the fabrication of metallic rods the metal typically is first cast by a caster into an elongated bar shape and then conveyed to a rolling mill where the bar is drawn and rolled into a rod. As the bar emerges from the caster its corner regions often have excess flashing and casting voids. Upon entering the rolling mill the bar should have neither of these attributes since a structurally degrading imperfection would then be made in the rod formed from the bar at the mill. For this reason it has become a common practice to provide bar conditioning apparatus at a bar conditioning station located between the caster and rolling mill where corners of the bar are trimmed by cutting tools.
While passing through the bar conditioning station between the caster and rolling mill the bar has not yet cooled sufficiently to assume a rigid condition. As a result it tends to wobble about in a rather serpentine fashion as it travels towards the mill. Since it is impractical to have the trimming tools themselves follow this random movement of the bar, it has been necessary to provide means for guiding the bar through the conditioning station a well defined path so that the trimming tools may continuously and uniformly trim a preselected portion of the bar corners.
FIG. 1 schematically illustrates bar conditioning apparatus which has heretofore typically been employed at the conditioning station. Here a metal bar 10 is seen to be guided into engagement with a bar corners trimming tool 12 by a lower guide wheel 14 and a pair of upper bar hold down rollers 16. The flanges of the guide wheels engage side portions of the bar thereby maintaining lateral alignment of the bar while the hold down rollers and guide wheel together cooperate to maintain vertical alignment. The trimming tools 12 trim the two upper corners of the bar forming trimmings or chips 18 in the process. Vertical steel brushes 20 and side steel brushes 22 are positioned in rotatable engagement with all sides of the bar to brush the trimmings 18 off of the bar prior to its entering the rolling mill.
FIG. 1 also is seen to illustrate certain problems associated with bar conditioning systems of the type there shown. One problem has been the fact that some of the trimmings made by the cutting tools have been pressed back into the semi-molten bar itself by one or more of the hold down or guide rollers located downstream from the trimming tools. When this occurs a structural inhomogenity is created in the bar which later will appear as a defect in a rod produced from the bar by the rolling mill. Though the vertical and horizontal brushes do brush away a large number of the trimmings they do not in practice clear all the trimmings. Furthermore, the brushes themselves present a problem in that some of the steel bristles 24 in time are pulled off the brushes and are held to a surface of the semi-molten bar. These bristles also produce structural inhomogenities in rods subsequently rolled from the bar. Thus, a dilemma is presented at the conditioning station of either allowing the bar as it moves in the direction shown by arrow 26 from the caster toward the rolling mill to wobble somewhat whereby the cutting tool 12 effects an uneven trim, or to guide the bar positively into engagement with the cutting tool in maintaining an accurate and uniform trim but with imperfections formed in the bar by impressed chips and bristles. This dilemma is one principle problem to which the present invention is addressed.